Measurement of the splashback feature around SZ-selected Galaxy clusters with DES, SPT, and ACT

We present a detection of the splashback feature around galaxy clusters selected using the Sunyaev–Zel’dovich (SZ) signal. Recent measurements of the splashback feature around optically selected galaxy clusters have found that the splashback radius, rsp, is smaller than predicted by N-body simulations. A possible explanation for this discrepancy is that rsp inferred from the observed radial distribution of galaxies is affected by selection effects related to the optical cluster-finding algorithms. We test this possibility by measuring the splashback feature in clusters selected via the SZ effect in data from the South Pole Telescope SZ survey and the Atacama Cosmology Telescope Polarimeter survey. The measurement is accomplished by correlating these cluster samples with galaxies detected in the Dark Energy Survey Year 3 data. The SZ observable used to select clusters in this analysis is expected to have a tighter correlation with halo mass and to be more immune to projection effects and aperture-induced biases, potentially ameliorating causes of systematic error for optically selected clusters. We find that the measured rsp for SZ-selected clusters is consistent with the expectations from simulations, although the small number of SZ-selected clusters makes a precise comparison difficult. In agreement with previous work, when using optically selected redMaPPer clusters with similar mass and redshift distributions, rsp is ∼2σ smaller than in the simulations. These results motivate detailed investigations of selection biases in optically selected cluster catalogues and exploration of the splashback feature around larger samples of SZ-selected clusters. Additionally, we investigate trends in the galaxy profile and splashback feature as a function of galaxy colour, finding that blue galaxies have profiles close to a power law with no discernible splashback feature, which is consistent with them being on their first infall into the cluster

Spatial distribution of woody plants in relation to mistletoe-infected Vachellia karroo trees in a semi-arid African savanna

By increasing resource heterogeneity, mistletoe-infected trees can restructure plant community processes and distribution patterns. No information is available on how mistletoe-infected Vachellia (Acacia) karroo trees within V. karroo dominated stands are spatially distributed, and on how they influence the spatial patterns of their surrounding conspecifics and heterospecifics. Each woody plant was stem mapped using a cartesian plane (x, y) within three 50×50 m plots located in V. karroo dominated stands in a semi-arid savanna, South West Zimbabwe. Pair correlations g(r) were used for the univariate analysis and Poisson process null models were applied to quantify and detect overall departure from randomness. For the bivariate analysis, pair correlations g12(r) under the null model of independence were used, whilst the mark correlation function (kmm(r)) was used to analyse the correlation of tree canopy area and mistletoe infection intensity. For each plot, size class distributions, based on tree height and basal stem diameter displayed negative J curves, with steep negative regression slopes across the size classes, clearly indicating a strongly recruiting population of V. karroo. The univariate patterns of all trees (infected and non-infected) were consistent with a random pattern, which is attributed to unsystematic mistletoe seed dispersal by birds. The univariate analysis of all woody plants (adults and juveniles) exhibited aggregation at small spatial scales due to the high abundance of clustered seedlings and saplings. At small spatial scales, understory woody plants (both conspecifics and non-conspecifics) were positively associated with mistletoe-infected trees due to mistletoephily which is the facilitation (or nurse protégé interactions) within the more resource-rich mistletoe-infected tree subcanopies. These results provide strong evidence suggesting that the variations in spatial pattern modification by mistletoe-infected trees could further increase spatial heterogeneity in this semi-arid savanna. As such, by increasing heterogeneity, mistletoe-infected trees can increase the resilience of semi-arid savannas in the face of perturbations and stochastic events

Oculopharyngeal muscular dystrophy. Phenotypic and genotypic studies in a UK population

Oculopharyngeal muscular dystrophy (OPMD) is an autosomal dominant disorder of late onset that commonly presents with ptosis and dysphagia. The genetic basis of the condition has been identified recently as a stable trinucleotide repeat expansion in exon 1 of the poly(A) binding protein 2 gene (PABP2), in which (GCG)6 is the normal repeat length. The prevalence of OPMD is greatest in patients of French-Canadian origin. It is not clear if expansion repeat length is a reliable test in other populations. In this study, we analysed the phenotypic and genotypic characteristics of 31 patients with OPMD in the UK. Ptosis was the first reported symptom in two-thirds of the patients, and half of the subjects studied had evidence of ophthalmoplegia. All but one family had a pathological expansion in the PABP2 gene, ranging from (GCG)8 to (GCG)13. In contrast to the French-Canadian population, (GCG)10 was almost as common as (GCG)9, evidence against a strong founder effect in the UK population. There was a weak association between repeat length and age of disease onset. Patients with longer repeat lengths, such as (GCG)13, developed severe limb weakness early in the disease. We were unable to detect the (GCG)7 polymorphism in over 200 normal controls, suggesting that the frequency of this expansion is lower than that found in the French-Canadian population. One family was negative for the expansion. Affected members presented with the classical features of OPMD, namely ptosis, dysphagia and cytoplasmic inclusions on muscle biopsy, although with some atypical features, such as early age of onset, high serum levels of creatine kinase and a profound ophthalmoplegia. This family is an example of a GCG expansion-negative oculopharyngeal syndrome requiring further genetic investigation. We conclude that PABP2 analysis is a reliable non-invasive diagnostic test for OPMD in the UK population

Anisotropic range image integration

Abstract. Obtaining high-quality 3D models of real world objects is an important task in computer vision. A very promising approach to achieve this is given by variational range image integration methods: They are able to deal with a substantial amount of noise and outliers, while regularising and thus creating smooth surfaces at the same time. Our paper extends the state-of-the-art approach of Zach et al. (2007) in several ways: (i) We replace the isotropic space-variant smoothing behaviour by an anisotropic (direction-dependent) one. Due to the directional adaptation, a better control of the smoothing with respect to the local structure of the signed distance field can be achieved. (ii) In order to keep data and smoothness term in balance, a normalisation factor is introduced. As a result, oversmoothing of locations that are seen seldom is prevented. This allows high quality reconstructions in uncontrolled capture setups, where the camera positions are unevenly distributed around an object. (iii) Finally, we use the more accurate closest signed distances instead of directional signed distances when converting range images into 3D signed distance fields. Experiments demonstrate that each of our three contributions leads to clearly visible improvements in the reconstruction quality.

The impact of elephants (Loxodonta africana) on the Baobab (Adansonia digitata) in a semi-arid savanna

The impacts of the expanding African elephant (Loxodonta africana) population in southern Africa leads to a shift in savanna vegetation community composition and structure. However, little has been done to understand the effect of elephants on the structure of keystone tree species like the baobab. We sampled two protected areas in Southeast lowveld of Zimbabwe to quantify the impact of elephants on the baobab (Adansonia digitata L.), one area with elephants (Save Valley Conservancy: SVC) and the other without elephants (Chipinge Safari Area: CSA). Data on elephant damage, baobab density, and structural variables (tree height, stem basal area, and canopy cover) were collected in seven 1 km2 plots. Baobab damage was classed into four categories, i) new, ii) old, iii) very old, and iv) none, to have a time series interpretation. Distances of every baobab tree from spatial variables, nearest management road, perennial water source and conservancy boundary were measured. Baobabs in the absence of elephants (CSA) were taller with higher basal area and canopy cover than those where elephants were present (SVC). Although SVC baobabs had smaller structural variables compared with CSA, their density was much higher 1.69 ha-1 compared with 0.94 ha-1 for CSA. More baobabs in the smaller size classes for SVC suggests that recruitment was higher than CSA. No elephant damage was observed in the CSA although 23 % of baobabs showed signs of very old harvesting of bark by humans. All trees in SVC showed signs of elephant damage in either trunks or canopies, with most of damage classed as very old. Baobab damage decreased with distance from roads and perennial water sources while it increased with distance from conservancy boundary. Our results demonstrate that elephants have a great impact on baobab structure but not necessarily recruitment as indicated by the presence of some baobabs in smaller size classes, suggesting that other factors may be more important in determining recruitment of this keystone species

Systematics of the Pacific monkey-faced bats (Chiroptera : Pteropodidae), with a new species of Pteraloplex and a new Fijian genus

Copyright © 2005 The Natural History MuseumThe fruit-bat genus Pteralopex comprises the monkey-faced bats, a group of six endangered species found only in old-growth forests on certain islands in the south-west Pacific (the Solomon Islands and Fiji). The taxonomy of the genus is reviewed in detail and updated accordingly. Two ‘cryptic’ biological species are shown to occur in sympatry on both Bougainville and Choiseul in the northern Solomon Islands (corresponding to Pteralopex anceps Andersen, 1909 and a previously undescribed species) and each is accordingly described and reviewed. A new genus (Mirimiri) is erected for the Fijian monkey-faced bat (formerly Pteralopex acrodonta), which differs greatly both morphologically and genetically from species of Pteralopex in the Solomon Islands. Ecomorphological differences between sympatric Pteralopex species are briefly reviewed, including potential differences in functional morphology and feeding ecology. Geographic patterns of occurrence and future survey priorities for monkey-faced bats are also discussed.Kristofer M. Helge